High-strength hard alloy and preparation method thereof

Abstract

The invention discloses a high-strength hard alloy and a preparation method thereof, and relates to the technical field of hard alloys. The preparation method of the high-strength hard alloy comprises the following steps that (1) WC coarse grains, WC fine grains, Co powder, titanium carbide and chromium carbide are added into a planetary ball mill, a forming agent is added for ball milling, and a mixture is obtained; (2) placing the mixture in a mold, and performing compression molding to obtain a green body; and (3) sintering the green body to obtain the high-strength hard alloy. The prepared hard alloy has excellent bending strength and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, specifically to a high-strength cemented carbide and its preparation method. Background Technology

[0002] Cemented carbide, due to its excellent properties such as high hardness, high strength, wear resistance, and corrosion resistance, is widely used in high-end manufacturing fields such as cutting tools, mining machinery, oil and gas drilling, and precision molds. However, with the increasing demands of modern industry on material performance, traditional cemented carbide is facing challenges in synergistically optimizing green strength and corrosion resistance. Currently, cemented carbide forming commonly uses traditional forming agents such as paraffin wax, polyvinyl alcohol, or polyethylene glycol. These traditional forming agents have weak interfacial bonding with WC and Co powders, resulting in insufficient green strength and susceptibility to cracking during handling. Furthermore, the forming agent completely volatilizes during the debinding stage, failing to positively impact the final alloy properties (such as corrosion resistance). Therefore, developing a multifunctional forming agent that can simultaneously improve green strength and enhance corrosion resistance is of great significance for improving the strength and corrosion resistance of cemented carbide.

[0003] Chinese invention patent CN109778046A discloses a method for preparing a low-cost, high-performance WC-Co cemented carbide with a mixed-crystalline structure. The method involves preparing a mixed powder using ammonium metatungstate, WC powder, graphite powder, and cobalt powder as raw materials; adding deionized water; and then subjecting the mixture to ball milling, adding a forming agent, pressing, degreasing, and calcining processes, followed by sintering to obtain a WC-Co cemented carbide with a mixed-crystalline structure. The WC-Co cemented carbide prepared by this invention exhibits high hardness, bending strength, and fracture toughness, demonstrating good comprehensive mechanical properties; however, its corrosion resistance remains insufficient. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-strength cemented carbide and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a high-strength cemented carbide includes the following steps: (1) Add coarse WC, fine WC, Co powder, titanium carbide, and chromium carbide to a planetary ball mill, add a forming agent, and ball mill to obtain a mixture; (2) Place the mixture in a mold and press it into shape to obtain a green embryo; (3) The green blank is sintered to obtain a high-strength cemented carbide; The molding agent is prepared by the following method: S1: 3,5-Diaminophenylboronic acid reacts with diethyl (2-chloroethyl)phosphonate to generate intermediate 1; the reaction equation is shown below: S2: Intermediate 1 reacts with 1,2-epoxy-5-hexene to generate intermediate 2; the reaction equation is shown below: S3: Intermediate 2 reacts with 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide under the action of a photoinitiator to generate a molding agent. The reaction equation is shown below:

[0006] In step (1), the weight percentage of coarse WC crystals is 40-50 parts, the weight percentage of fine WC crystals is 30-40 parts, the weight percentage of Co powder is 6-10 parts, the weight percentage of titanium carbide is 0.4-0.6 parts, and the weight percentage of chromium carbide is 0.5-0.8 parts.

[0007] In step S1, the molar ratio of 3,5-diaminophenylboronic acid to diethyl (2-chloroethyl)phosphonate is 1:(2.01-2.03).

[0008] In step S2, the molar ratio of intermediate 1 to 1,2-epoxy-5-hexene is 1:(2.03-2.05).

[0009] In step S3, the molar ratio of intermediate 2 to 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide is 1:(2.04-2.08).

[0010] The reaction temperature for step S1 is 50-60℃ and the reaction time is 6-8h; the reaction temperature for step S2 is 70-80℃ and the reaction time is 3-5h.

[0011] In step S3, the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone.

[0012] In step (1), the amount of molding agent used is 4wt%-6wt% of the total amount of other raw materials excluding molding agent.

[0013] In step (2), the pressing pressure is 200-300 MPa and the pressing time is 20-30 min.

[0014] The specific sintering process is as follows: the green blank is sintered in a sintering furnace under vacuum and nitrogen protective atmosphere in stages, and then held at 350℃, 1000℃ and 1450℃ in sequence to complete the sintering and obtain a high-strength cemented carbide.

[0015] A high-strength cemented carbide is prepared by the above method.

[0016] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: The cemented carbide prepared by this invention exhibits excellent bending strength and corrosion resistance. The forming agent used in the preparation of the cemented carbide enhances the alloy's strength and corrosion resistance through the synergistic effect of benzene rings, boric acid, siloxanes, phosphate esters, flexible alkyl chains, amides, and hydroxyl functional groups. Attached Figure Description

[0017] Figure 1 The image shows the proton NMR spectrum of the molding agent prepared in Example 2.

[0018] Figure 2 The image shows a high-resolution mass spectrum of the molding agent prepared in Example 2. Detailed Implementation

[0019] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0020] Example 1: Preparation of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide Under nitrogen protection, 400 ml of anhydrous dichloromethane, 0.1 mol of 4-mercaptophenylbutyric acid, 22.9 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 13.8 g of N-hydroxysuccinimide were mixed and stirred in an ice bath for 1 h. Then, 0.103 mol of 3-aminopropyltrimethoxysilane was slowly added dropwise over 30 min. The mixture was heated to 30 °C and reacted for 12 h. After filtration, the mixture was distilled under reduced pressure at 30 °C for 1 h. The final product was obtained using a mixture of 180 ml of ethyl acetate and anhydrous ethanol (V... 乙酸乙酯 :V 无水乙醇 Recrystallization of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide (8:2 ratio) and vacuum drying at 60 °C for 12 h yielded 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide; its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO-) d 6 ) δ 7.41 (s, 1H), 7.28-7.21 (m, 2H), 7.19 (s, 1H), 7.16-7.08(m, 2H), 3.52 (s, 9H), 3.11 (t, J = 6.5 Hz, 2H), 2.64 (t, J = 7.0 Hz, 2H),2.19 (t, J = 6.4 Hz, 2H), 1.80 (t, J = 6.1 Hz, 2H), 1.68-1.53 ​​(m, 2H), 1.07-0.93 (m, 2H); HRMS (m / z):358.1436[M+H] + The reaction equation is shown below:

[0021] Example 2 Preparation of molding agent S1: Under nitrogen protection, 400 ml of anhydrous acetonitrile, 0.1 mol of 3,5-diaminophenylboronic acid, and 0.201 mol of diethyl (2-chloroethyl)phosphonate were stirred and mixed. 0.21 mol of potassium carbonate was added, and the mixture was reacted at 50 °C for 8 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 50 °C for 2 h. The crude product was purified by silica gel column chromatography (V... 二氯甲烷 :V 甲醇 The ratio of crude oil to distillate was 10:1. The intermediate was obtained by vacuum distillation at 40℃ for 1 hour; its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6 ) δ 8.06 (s, 2H), 7.25 (d, J = 6.0Hz, 2H), 6.31 (t, J = 5.0 Hz, 1H), 5.94 (s, 2H), 3.97 (s, 8H), 3.48 (d, J =5.5 Hz, 4H), 2.19 (m, 4H), 1.27 (t, J = 6.3 Hz, 12H); HRMS (m / z):481.1958[M+H] + ; S2: Under nitrogen protection, 350 ml of anhydrous DMF and 0.1 mol of intermediate 1 were stirred and mixed. 0.203 mol of 1,2-epoxy-5-hexene was slowly added dropwise over 20 min. The mixture was then heated to 70 °C and reacted for 5 h. After distillation under reduced pressure at 70 °C for 1 h, 300 ml of cold anhydrous n-hexane was added and stirred to precipitate the mixture. The precipitate was filtered, and the filter cake was washed with cold anhydrous n-hexane (2 × 80 ml). The mixture was then dried under vacuum at 60 °C for 8 h to obtain intermediate 2. Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 8.09 (s, 2H), 7.26 (d, J =6.0 Hz, 2H), 6.14 (t, J = 5.0 Hz, 1H), 5.62 (m, 2H), 5.09-4.95 (m, 4H), 4.69(d, J = 5.0 Hz, 2H), 3.99 (s, 8H), 3.65 (d, J = 5.0 Hz, 2H), 3.50 (d, J =12.4 Hz, 2H), 3.35 (d, J = 12.4 Hz, 2H), 3.18-3.02 (m, 4H), 2.24-2.06 (m,8H), 1.73-1.55 (m, 4H), 1.27 (t, J = 6.2 Hz, 12H); HRMS (m / z):677.3429[M+H] + ; S3: Under nitrogen protection, 700 ml of anhydrous tetrahydrofuran, 0.1 mol of intermediate 2, 0.204 mol of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide, and 1.03 g of 2,2-dimethoxy-2-phenylacetophenone were stirred and mixed. The mixture was then irradiated at 100 W under 365 nm UV light for 30 min at room temperature, followed by vacuum distillation at 40 °C for 2 h. 550 ml of cold anhydrous diethyl ether was added, and the mixture was stirred to precipitate. The precipitate was filtered, washed with 100 ml of cold anhydrous diethyl ether, and dried under vacuum at 40 °C for 12 h to obtain the molding agent. Its proton NMR spectrum is shown below. Figure 1 As shown, the proton NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 8.09 (s, 2H), 7.41(s, 2H), 7.26 (d, J = 5.0 Hz, 2H), 7.22-7.15 (m, 4H), 7.12-7.05 (m, 4H), 6.14(t, J = 4.0 Hz, 1H), 4.70 (d, J = 5.0 Hz, 2H), 3.99 (s, 8H), 3.69 (d, J = 4.9Hz, 2H), 3.52 (s, 18H), 3.49 (s, 2H), 3.35 (d, J = 12.4 Hz, 2H), 3.18-2.88(m, 12H), 2.64 (q, J = 6.9 Hz, 4H), 2.19 (d, J = 3.6 Hz, 4H), 2.11 (d, J = 2.8 Hz, 4H), 1.80 (d, J = 4.1 Hz, 4H), 1.70–1.38 (m, 16H), 1.27 (t, J = 6.2 Hz, 12H), 1.07–0.92 (m, 4H); its high-resolution mass spectrum is shown below. Figure 2 As shown, the mass spectrometry data are as follows: HRMS (m / z): 1391.6287 [M+H] + .

[0022] Example 3 Preparation of molding agent S1: Under nitrogen protection, 400 ml of anhydrous acetonitrile, 0.1 mol of 3,5-diaminophenylboronic acid, and 0.202 mol of diethyl (2-chloroethyl)phosphonate were stirred and mixed. 0.21 mol of potassium carbonate was added, and the mixture was reacted at 55 °C for 7 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 50 °C for 2 h. The crude product was purified by silica gel column chromatography (V... 二氯甲烷 :V 甲醇 =10:1), distilled under reduced pressure at 40℃ for 1 h to obtain intermediate 1; S2: Under nitrogen protection, 350 ml of anhydrous DMF and 0.1 mol of intermediate 1 were stirred and mixed. 0.204 mol of 1,2-epoxy-5-hexene was slowly added dropwise over 20 min. The mixture was then heated to 75 °C and reacted for 4 h. The mixture was then distilled under reduced pressure at 70 °C for 1 h. 300 ml of cold anhydrous n-hexane was added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with cold anhydrous n-hexane (2 × 80 ml). The mixture was then dried under vacuum at 60 °C for 8 h to obtain intermediate 2. S3: Under nitrogen protection, 700 ml of anhydrous tetrahydrofuran, 0.1 mol of intermediate 2, 0.206 mol of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide, and 1.03 g of 2,2-dimethoxy-2-phenylacetophenone were stirred and mixed. The mixture was then irradiated at 100 W under 365 nm ultraviolet light for 30 min at room temperature, followed by vacuum distillation at 40 °C for 2 h. 550 ml of cold anhydrous diethyl ether was added, and the mixture was stirred to precipitate the precipitate. The precipitate was filtered, washed with 100 ml of cold anhydrous diethyl ether, and dried under vacuum at 40 °C for 12 h to obtain the molding agent.

[0023] Example 4 Preparation of molding agent S1: Under nitrogen protection, 400 ml of anhydrous acetonitrile, 0.1 mol of 3,5-diaminophenylboronic acid, and 0.203 mol of diethyl (2-chloroethyl)phosphonate were stirred and mixed. 0.21 mol of potassium carbonate was added, and the mixture was reacted at 60 °C for 6 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 50 °C for 2 h. The crude product was purified by silica gel column chromatography (V... 二氯甲烷 :V 甲醇 =10:1), distilled under reduced pressure at 40℃ for 1 h to obtain intermediate 1; S2: Under nitrogen protection, 350 ml of anhydrous DMF and 0.1 mol of intermediate 1 were stirred and mixed. 0.205 mol of 1,2-epoxy-5-hexene was slowly added dropwise over 20 min. The mixture was then heated to 80 °C and reacted for 3 h. The mixture was then distilled under reduced pressure at 70 °C for 1 h. 300 ml of cold anhydrous n-hexane was added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with cold anhydrous n-hexane (2 × 80 ml). The mixture was then dried under vacuum at 60 °C for 8 h to obtain intermediate 2. S3: Under nitrogen protection, 700 ml of anhydrous tetrahydrofuran, 0.1 mol of intermediate 2, 0.208 mol of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide, and 1.03 g of 2,2-dimethoxy-2-phenylacetophenone were stirred and mixed. The mixture was then irradiated at 100 W under 365 nm ultraviolet light for 30 min at room temperature, followed by vacuum distillation at 40 °C for 2 h. 550 ml of cold anhydrous diethyl ether was added, and the mixture was stirred to precipitate the precipitate. The precipitate was filtered, washed with 100 ml of cold anhydrous diethyl ether, and dried under vacuum at 40 °C for 12 h to obtain the molding agent.

[0024] Example 5: Preparation of high-strength cemented carbide (1) Add 400g of coarse WC, 300g of fine WC, 60g of Co powder, 4g of titanium carbide, and 5g of chromium carbide to a planetary ball mill, add 31.4g of forming agent, use grinding balls with a diameter of 5mm and 3mm, the weight ratio of 5mm grinding balls to 3mm grinding balls is 2:1, the ball-to-material ratio is 15:1, grind at 500rpm for 10min, stop for 15min, grind again at 500r / min for 15min to obtain a mixture; (2) Place the mixture in a mold and press it under a pressure of 200 MPa for 30 minutes using a cold isostatic press to obtain a green embryo; (3) Add the green blank to the vacuum sintering furnace, keep the furnace cavity in a vacuum state, fill with nitrogen as a protective atmosphere, raise the temperature to 350°C at a rate of 0.5°C / min, hold for 2 hours, raise the temperature to 1000°C at a rate of 3°C / min, hold for 1 hour, raise the temperature to 1450°C at a rate of 5°C / min, hold for 1 hour, and obtain a high-strength cemented carbide.

[0025] Example 6 Preparation of high-strength cemented carbide (1) Add 450g of coarse WC, 350g of fine WC, 80g of Co powder, 5g of titanium carbide, and 6g of chromium carbide to a planetary ball mill, add 45.9g of forming agent, use grinding balls with a diameter of 5mm and 3mm, the weight ratio of 5mm grinding balls to 3mm grinding balls is 2:1, the ball-to-material ratio is 15:1, grind at 500rpm for 10min, stop for 15min, grind again at 500r / min for 15min to obtain a mixture; (2) Place the mixture in a mold and press it for 25 minutes at 250 MPa using a cold isostatic press to obtain a green embryo; (3) Add the green blank to the vacuum sintering furnace, keep the furnace cavity in a vacuum state, fill with nitrogen as a protective atmosphere, raise the temperature to 350°C at a rate of 0.5°C / min, hold for 2 hours, raise the temperature to 1000°C at a rate of 3°C / min, hold for 1 hour, raise the temperature to 1450°C at a rate of 5°C / min, hold for 1 hour, and obtain a high-strength cemented carbide.

[0026] Example 7 Preparation of high-strength cemented carbide (1) Add 500g of coarse WC, 400g of fine WC, 100g of Co powder, 6g of titanium carbide and 8g of chromium carbide to a planetary ball mill, add 63g of forming agent, use grinding balls with a diameter of 5mm and 3mm, the weight ratio of 5mm grinding balls to 3mm grinding balls is 2:1, the ball-to-material ratio is 15:1, grind at 500rpm for 10min, stop for 15min, grind again at 500r / min for 15min to obtain a mixture; (2) Place the mixture in a mold and press it for 20 minutes at 300 MPa using a cold isostatic press to obtain a green embryo; (3) Add the green blank to the vacuum sintering furnace, keep the furnace cavity in a vacuum state, fill with nitrogen as a protective atmosphere, raise the temperature to 350°C at a rate of 0.5°C / min, hold for 2 hours, raise the temperature to 1000°C at a rate of 3°C / min, hold for 1 hour, raise the temperature to 1450°C at a rate of 5°C / min, hold for 1 hour, and obtain a high-strength cemented carbide.

[0027] Comparative Example 1 The preparation method of the high-strength cemented carbide is basically the same as that in Example 6, except that the forming agent is replaced with an equal weight of the forming agent prepared by the following method: The preparation method of the molding agent is basically the same as that in Example 3, except that 3,5-diaminophenylboronic acid in step S1 is replaced with an equimolar amount of m-phenylenediamine.

[0028] Comparative Example 2 The preparation method of the high-strength cemented carbide is basically the same as that in Example 6, except that the forming agent is replaced with an equal weight of the forming agent prepared by the following method: The preparation method of the molding agent is basically the same as that in Example 3, except that 3,5-diaminophenylboronic acid in step S1 is replaced with 0.2 mol of 3-aminophenylboronic acid; the amount of 1,2-epoxy-5-hexene in step S2 is replaced with 0.104 mol; and the amount of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide in step S3 is replaced with 0.106 mol.

[0029] Comparative Example 3 The preparation method of the high-strength cemented carbide is basically the same as that in Example 6, except that the forming agent is replaced with an equal weight of the forming agent prepared by the following method: A1: Under nitrogen protection, 200 ml of anhydrous acetonitrile and 0.1 mol of 3,5-diaminophenylboronic acid were stirred and mixed. 0.202 mol of 1,2-epoxy-5-hexene was slowly added dropwise over 20 min. The mixture was heated to 60 °C and reacted for 5 h. The mixture was then distilled under reduced pressure at 50 °C for 1 h. 150 ml of cold anhydrous n-hexane was added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with cold anhydrous n-hexane (2 × 30 ml). The mixture was then dried under vacuum at 60 °C for 8 h to obtain intermediate A. A2: Under nitrogen protection, 550 ml of anhydrous tetrahydrofuran, 0.1 mol of intermediate A, 0.206 mol of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide, and 1.03 g of 2,2-dimethoxy-2-phenylacetophenone were stirred and mixed. The mixture was then irradiated with 100 W of 365 nm ultraviolet light for 30 min at room temperature, followed by vacuum distillation at 40 °C for 2 h. 450 ml of cold anhydrous diethyl ether was added, and the mixture was stirred to precipitate the precipitate. The precipitate was filtered, washed with 80 ml of cold anhydrous diethyl ether, and dried under vacuum at 40 °C for 12 h to obtain intermediate B. A3: Under nitrogen protection, 650 ml of anhydrous acetonitrile, 0.1 mol of intermediate B, and 0.101 mol of diethyl (2-chloroethyl)phosphonate were stirred and mixed. 0.103 mol of potassium carbonate was added, and the mixture was reacted at 60°C for 8 hours. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 50°C for 2 hours. The final product was obtained using a mixture of 600 ml of ethyl acetate and anhydrous ethanol (V... 乙酸乙酯 :V无水乙醇 The mixture was recrystallized at a ratio of 7:3 and dried under vacuum at 60°C for 12 hours to obtain the molding agent.

[0030] Comparative Example 4 The preparation method of the high-strength cemented carbide is basically the same as that in Example 6, except that the forming agent is replaced with an equal weight of the forming agent prepared by the following method: The preparation method of the molding agent is basically the same as that in Example 3, except that the amount of 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide in step S3 is replaced with 0.106 mol.

[0031] Comparative Example 5 The preparation method of the high-strength cemented carbide is basically the same as that in Example 6, except that the forming agent is replaced with an equal weight of the forming agent prepared by the following method: The preparation method of the molding agent is basically the same as that in Example 3, except that 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide in step S3 is replaced with an equimolar amount of 5-mercapto-N-(3-trimethoxysilylpropyl)pentamide. 5-Mercapto-N-(3-trimethoxysilylpropyl)pentanamide was prepared by the following method: Under nitrogen protection, 400 ml of anhydrous dichloromethane, 0.1 mol of 5-mercaptovalerate, 22.9 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 13.8 g of N-hydroxysuccinimide were stirred and mixed thoroughly. Then, 0.103 mol of 3-aminopropyltrimethoxysilane was slowly added dropwise over 30 min. The reaction was carried out at 30 °C for 12 h, filtered, and distilled under reduced pressure at 30 °C for 1 h. The crude product was purified by silica gel chromatography (V... 二氯甲烷 :V 甲醇 =15:1), distilled under reduced pressure at 30℃ for 1 h to obtain 5-mercapto-N-(3-trimethoxysilylpropyl)pentanamide.

[0032] The chemical structural formula of 5-mercapto-N-(3-trimethoxysilylpropyl)pentanamide is as follows: The coarse WC (coarse-grained tungsten carbide) used in the embodiments and comparative examples of this application has a particle size distribution of 2-5 μm; the fine WC (fine-grained tungsten carbide) has a particle size distribution of 0.3-1 μm; the Co powder has a particle size distribution of 1-2 μm; the titanium carbide has a particle size distribution of 1-3 μm; and the chromium carbide has a particle size distribution of 1-2 μm.

[0033] The high-strength cemented carbides prepared in Examples 5-7 and Comparative Examples 1-5 were tested, and the test results are shown in Table 1.

[0034] Bending strength test: The cemented carbide samples prepared in Examples 5-7 and Comparative Examples 1-5 were cut into specimens with dimensions of 20mm × 6mm × 5.2mm. The bending strength was determined using a universal testing machine with a fixture span of 14.5mm and a loading speed of 0.5mm / min. The bending strength was calculated according to the following formula: In the formula, R is the bending strength (MPa); F is the load that the specimen bears when it breaks (N); L is the span of the fixture (mm); b is the width of the specimen (mm); and h is the thickness of the specimen (mm).

[0035] Corrosion resistance test: The cemented carbides prepared in Examples 5-7 and Comparative Examples 1-5 were subjected to salt spray tests in a JST-120 salt spray test chamber. The test temperature was 35℃, the corrosive medium was a 5wt% NaCl solution, the spraying method was continuous spraying, and the salt spray deposition rate was 1ml / 80cm. 2 •h, test duration 1500h, observe whether the alloy has rust after the test.

[0036] Table 1 Performance Test Data As can be seen from Table 1, the cemented carbide prepared in Examples 5-7 of this application has excellent bending strength and corrosion resistance.

[0037] The forming agent used in the preparation of cemented carbide in Examples 5-7 of this application contains benzene rings, boric acid, siloxanes, phosphate esters, amides, and hydroxyl functional groups. These components function in both the forming and sintering stages of cemented carbide preparation, significantly improving the alloy's bending strength and corrosion resistance. During the forming stage, the boric acid and phosphate ester groups in the forming agent molecules react with Co... 2+ Ti 4+A dual chelate anchoring is formed on the powder surface, with amide bonds and hydroxyl groups constructing a hydrogen bond network. At the same time, the benzene ring in the molecule provides rigid skeletal support, jointly improving the green strength and molding uniformity. During sintering, the forming agent undergoes thermal decomposition, and the siloxane structure pyrolyzes to generate the SiO2 interface phase, forming a reinforced transition layer at the WC / Co grain boundary, improving the grain boundary bonding strength and inhibiting crack initiation. The boric acid structure is transformed into boron oxide and boron-oxygen bonded layer, constructing a dense and corrosion-resistant protective phase at the grain boundary, inhibiting the dissolution of the Co phase in the corrosive environment. The phosphorus oxide formed by the thermal decomposition of phosphate ester can promote grain boundary densification, and at the same time form a stable phosphate passivation layer at the grain boundary, which, together with boron oxide and siloxane residues, constructs a composite protective interface, thereby further improving the bending strength and corrosion resistance of the cemented carbide. The forming agent used in Comparative Example 3 contains only one molecule of phosphate ester structure. On the one hand, during the forming process, the anchoring effect between the forming agent molecule and the powder is weakened, resulting in a decrease in the strength of the alloy. On the other hand, during the sintering process, the ability to generate a phosphate passivation layer decreases, and the synergistic corrosion resistance with boron oxide and siloxane residues is weakened, resulting in a decrease in the corrosion resistance of the prepared alloy.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength cemented carbide, characterized in that, Includes the following steps: (1) Add coarse WC, fine WC, Co powder, titanium carbide, and chromium carbide to a planetary ball mill, add a forming agent, and ball mill to obtain a mixture; (2) Place the mixture in a mold and press it into shape to obtain a green embryo; (3) The green blank is sintered to obtain a high-strength cemented carbide; The molding agent is prepared by the following method: S1: 3,5-Diaminophenylboronic acid reacts with diethyl (2-chloroethyl)phosphonate to generate intermediate 1; S2: Intermediate 1 reacts with 1,2-epoxy-5-hexene to generate intermediate 2; S3: Intermediate 2 reacts with 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide under the action of a photoinitiator to generate a molding agent.

2. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step (1), the weight percentage of coarse WC crystals is 40-50 parts, the weight percentage of fine WC crystals is 30-40 parts, the weight percentage of Co powder is 6-10 parts, the weight percentage of titanium carbide is 0.4-0.6 parts, and the weight percentage of chromium carbide is 0.5-0.8 parts.

3. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step S1, the molar ratio of 3,5-diaminophenylboronic acid to diethyl (2-chloroethyl)phosphonate is 1:(2.01-2.03).

4. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step S2, the molar ratio of intermediate 1 to 1,2-epoxy-5-hexene is 1:(2.03-2.05).

5. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step S3, the molar ratio of intermediate 2 to 4-(4-mercaptophenyl)-N-(3-trimethoxysilylpropyl)butyramide is 1:(2.04-2.08).

6. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, The reaction temperature for step S1 is 50-60℃ and the reaction time is 6-8h; the reaction temperature for step S2 is 70-80℃ and the reaction time is 3-5h.

7. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step S3, the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone.

8. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step (1), the amount of molding agent used is 4wt%-6wt% of the total amount of other raw materials excluding molding agent.

9. The method for preparing a high-strength cemented carbide according to claim 1, characterized in that, In step (2), the pressing pressure is 200-300 MPa and the pressing time is 20-30 min.

10. A high-strength cemented carbide, characterized in that, It is prepared by the method described in any one of claims 1-9.

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